.\" zip_file_set_encryption.mdoc -- set encryption method for file
.\" Copyright (C) 2016-2021 Dieter Baron and Thomas Klausner
.\"
.\" This file is part of libzip, a library to manipulate ZIP files.
.\" The authors can be contacted at <libzip@nih.at>
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.Dd April 2, 2020
.Dt ZIP_FILE_SET_ENCRYPTION 3
.Os
.Sh NAME
.Nm zip_file_set_encryption
.Nd set encryption method for file in zip
.Sh LIBRARY
libzip (-lzip)
.Sh SYNOPSIS
.In zip.h
.Ft int
.Fn zip_file_set_encryption "zip_t *archive" "zip_uint64_t index" "zip_uint16_t method" "const char *password"
.Sh DESCRIPTION
The
.Fn zip_file_set_encryption
function sets the encryption method for the file at position
.Ar index
in the zip archive to
.Ar method
using the password
.Ar password .
The
.Ar method
is the same as returned by
.Xr zip_stat 3 .
For the
.Ar method
argument, currently only the following values are supported:
.Bl -tag -width ZIP_CM_DEFLATE_XX
.It Dv ZIP_EM_NONE
No encryption.
.It Dv ZIP_EM_AES_128
Winzip AES-128 encryption.
.It Dv ZIP_EM_AES_192
Winzip AES-192 encryption.
.It Dv ZIP_EM_AES_256
Winzip AES-256 encryption.
.It Dv ZIP_EM_TRAD_PKWARE
Traditional PKWare encryption.
Do not use this method, it is not secure.
It is only provided for backwards compatibility.
.El
.Pp
If
.Ar password
is
.Dv NULL ,
the default password provided by
.Xr zip_set_default_password 3
is used.
.Pp
The current encryption method for a file in a zip archive can be
determined using
.Xr zip_stat 3 .
.Sh RETURN VALUES
Upon successful completion 0 is returned.
Otherwise, \-1 is returned and the error information in
.Ar archive
is set to indicate the error.
.Sh ERRORS
.Fn zip_file_set_encryption
fails if:
.Bl -tag -width Er
.It Bq Er ZIP_ER_ENCRNOTSUPP
Unsupported compression method requested.
.It Bq Er ZIP_ER_INVAL
.Ar index
is not a valid file index in
.Ar archive ,
or the argument combination is invalid.
.It Bq Er ZIP_ER_MEMORY
Required memory could not be allocated.
.It Bq Er ZIP_ER_RDONLY
Read-only zip file, no changes allowed.
.El
.Sh SEE ALSO
.Xr libzip 3 ,
.Xr zip_encryption_method_supported 3 ,
.Xr zip_fopen_encrypted 3 ,
.Xr zip_fopen_index_encrypted 3 ,
.Xr zip_set_default_password 3 ,
.Xr zip_stat 3
.Sh HISTORY
.Fn zip_file_set_encryption
was added in libzip 1.2.0.
.Sh AUTHORS
.An -nosplit
.An Dieter Baron Aq Mt dillo@nih.at
and
.An Thomas Klausner Aq Mt tk@giga.or.at
